Selective and/or faster removal of a coating from an underlying layer, and solar cell applications thereof

Abstract

A method for patterning a film pattern on a substrate includes forming a film pattern on a substrate surface, forming a coating over the substrate and the film pattern and inducing porosity or openings in the coating. At least a part of the coating overlying the film pattern is removed including etching at least one layer underlying the coating ahead of removing at least part of the coating.

What is claimed is: 
     
         1 . A method for patterning a film pattern on a substrate comprising:
 forming a film pattern on a substrate surface;   forming a coating over the substrate and the film pattern;   inducing porosity or openings in the coating; and   removing at least part of the coating overlying the film pattern including etching at least one layer underlying the coating ahead of removing at least part of the coating.   
     
     
         2 . The method of  claim 1  where the film pattern is formed by:
 forming a film, on a surface of the substrate; 
 forming an etch resist over the film; 
 etching the film in one or multiple steps including faster removal of a top layer of the at least one layer by etching an underlying layer of the at least one layer first; and 
 removal of the etch resist. 
 
     
     
         3 . The method of  claim 1  wherein the film pattern is formed by one of screen printing a metal paste, inkjet printing a nanoparticle metal ink and aerosol printing metal nanoparticles. 
     
     
         4 . The method of  claim 1  wherein the substrate and the coating avoid significantly interacting with etchants attacking the at least one layer. 
     
     
         5 . The method of  claim 1  wherein the etchant interacts with the film pattern and overlying coating leading to the partial or complete removal of the overlying coating, with the remaining overlying coating being unsupported. 
     
     
         6 . A structure on a surface on a substrate wherein a film pattern is surrounded by a coating and where no gap exists between the pattern and the surrounding coating. 
     
     
         7 . The method of  claim 1  wherein the substrate is a photovoltaic device. 
     
     
         8 . The method of  claim 1  wherein the film pattern forms a front and/or a back contact electrode of a solar cell. 
     
     
         9 . The method of  claim 1  further comprising subsequently electroplating the film pattern with metal to improve electrical conductivity of the metal grid. 
     
     
         10 . The method of  claim 1  wherein the coating is a dielectric optical antireflection layer. 
     
     
         11 . The method of  claim 1  wherein the dielectric coating is an optical reflecting layer. 
     
     
         12 . The method of  claim 2  wherein the patterned resist is directly-written and in-situ cured with no need for subsequent pattern mask exposure and developing. 
     
     
         13 . The method of  claim 12  wherein the patterning resist direct-write technique is ink jetting or screen-printing. 
     
     
         14 . The method of  claim 1  wherein the metal film pattern comprises multiple thin film metal layers of different or varying composition and thicknesses. 
     
     
         15 . The method of  claim 14  wherein the multiple thin film metal layers comprise one or more of the following metals or metal alloys: chromium, silver, copper, nickel, titanium, aluminum, nickel-vanadium, nickel-niobium, nickel-titanium, nickel-zirconium, nickel-chromium, nickel-platinum, nickel-aluminum, nickel-tungsten, titanium-tungsten, cobalt-nickel, chromium-cobalt-nickel, chromium-cobalt, chromium-nickel, chromium-silicon, chromium-copper, chromium-aluminum, aluminum-silicon-copper, aluminum-silicon, and aluminum-chromium. 
     
     
         16 . The method of  claim 5  where the metal film comprises a top metal film in a stack of multiple thin film metals, the top metal film being directly electroplate-able and consists of one of the following metal layers: silver, copper, nickel, chromium, nickel-niobium, nickel-vanadium, nickel-titanium, nickel-zirconium, nickel-chromium, nickel-platinum, nickel-aluminum, nickel-tungsten, chromium-cobalt-nickel, chromium-cobalt, chromium-nickel, chromium-silicon, chromium-copper and chromium-aluminum. 
     
     
         17 . The method of  claim 1  wherein the etching comprises the entire substrate being immersed in an etchant or the etchant being applied selectively to match the underlying film pattern; wherein the etchant passes through pinholes or openings in a top layer that is already present or introduced prior to this step by one of chemical, physical, electrical, and topographical methods. 
     
     
         18 . The method of  claim 1  wherein the substrate comprises a silicon wafer solar cell, one or both surfaces of which are textured to improve light trapping. 
     
     
         19 . The method of  claim 1  wherein the etching partially removes or disrupts the dielectric coating overlying the film pattern. 
     
     
         20 . The method of  claim 1  wherein the film pattern comprises a metal.